Final answer:
Watson and Crick's DNA model proposed a double helix structure with antiparallel polynucleotide chains held together by complementary base pairs and suggested a semi-conservative replication mechanism. Their predictions were instrumental in understanding DNA's role in heredity and protein synthesis.
Step-by-step explanation:
James Watson and Francis Crick's model of the DNA structure, revealed in 1953, included several structural predictions. They proposed a double helical structure for DNA. This double helix consists of two polynucleotide chains running antiparallel to each other, twisted in a spiral form. It was postulated that the amount of adenine (A) is equal to thymine (T), and the amount of guanine (G) is equal to cytosine (C), a relationship that became known as Chargaff's rules. The chains are held together by hydrogen bonds between pairs of bases: adenine pairs with thymine, and guanine pairs with cytosine. These base pairings are often referred to as complementary base pairs.
Additionally, Watson and Crick foresaw that the DNA replication could proceed in a semi-conservative manner, meaning that each of the two new DNA molecules would have one old and one new strand. This model not only provides a structural explanation of DNA but also sheds light on the molecular mechanisms of genetic transmission. The resulting structure suggests a method by which DNA can replicate itself and thus provide a mechanism for heredity. This conceptual breakthrough allowed for the understanding of genetic coding and protein synthesis, expanding the sphere of molecular biology.